July 3, 1879] 



NATURE 



2:9 



said to have been pierced three times by a vertical shaft. Yet 

 the coals are not anthracite. The Vobster pits are very fiery. 

 The Radstock pits, where the coal is horizontal, not so ; but they 

 are worked in higher beds. 



By reference to the Commissioner's report to Parliament, 1871, 

 it will be seen (p. 38) in Mr. Prestwich's report on the Nettle- 

 bridge Valley coals, where Vobster is situated, that my recollec- 

 tions are confirmed ; "bituminous coal " and "disturbed condi- 

 tion " being alike attributed to these coal beds. 



With respect to the general question of the mechanical theory 

 of earth-heat, I would respectfully refer Mr. Lesley to my 

 examination of the theory in the Philosophical Magazine for 

 October, 1875. O. FiSHER 



Harlton, Cambridge 



On the Origin of Certain Granitoid Rocks 



In a paper by me "On the Pre-Cambrian Rocks of Shropshire, '' 

 read before the Geological Society on the nth inst., I call 

 attention to certain granitoid and gneissicrocls in Primrose Hill, 

 at the south-west end of the Wrekin. Associated with these 

 metamorphic strata in such an irregular manner as to suggest an 

 eruptive origin is a compact felspathic rock with minute quartz 

 grains, which I at first presumed to be a quartz felsite. On 

 submitting specimens to Prof. Bonney, F.R.S., for microscopic 

 examination, he declared the reck to be clastic, and closely 

 allied to the halleflintas, which Dr. Hicks assigns to his Arvonian 

 group. Certain observations recently made in south-west Shrop- 

 shire, suggested to me a transition between the halleflinta and tlie 

 granitoid types, and, on communicating my suspicions to Prof. 

 Bonney, he stated that a similar connection had been suggested 

 by his microscopic examination. This morning I hammered 

 over Primrose Hill foot by foot, and I have the satisfaction of 

 announcing the fullest confirmation of our suspicions. In the 

 same block, the compact halleflinta is frequently mixed up with 

 granitoidite and homblendic gneiss. In some cases, the meta- 

 morphism has taken place only near the surface, as if produced 

 by atmospheric agencies ; in others the crystallisation occurs in 

 nests, while in others there is a gradual transition in mass from a 

 compact to a granitic structure. This passage of halleflinta into 

 granite has obviously important theoretical applications. 



Wellington, Salop, June 21 C. Callaway 



Vernal Migration, 1879 



Migrations of Birds 



I NOTICED some time ago a communication in Nature re- 

 specting this subject, stating that it would be instructive and 

 interesting alii e if naturalists would record any data they may 

 have collected on this subject. For years now this matter has 

 had my careful attention, and I therefore forward a few notes 

 for the last two seasons, and also put forward the hope that 

 observers stationed in other parts of the United Kingdom w ill 

 contribute information of a like nature. I would also say that 

 the weather noted applies to the night — the time, by the way, 

 generally chosen for migratory movements. 



Vernal Migration, 1878 

 Dates. Species. Remarks. 



April 4 ... Gray Wagtail In pairs on the trout streams for nest- 

 ing season. Weather clear, warm 

 westerly breezes. 



,, 4 ... Tree Pipit In full song and seen for first lime ; 



westerly breezes. 



,, 15 ... Redstart In full song in Encliffe Wood and 



Rivelln Valley ; warm westerly 

 breezes, clear. 



15 ... Willow Warbler Numerous, arrived during last night. 



"^'—-^---^ ... Numerous and full cf song. 



... In small numbers, westerly breezes, 



very warm, close. 

 ... One specimen seen ; westerly breezes, 



fine and clear. 

 ... Heard and saw flying ever the busiest 



streets of Sheffield at 4.30 A.M. 

 ... One heard ; dull and misty drizzling 

 rain, W.S.W. 

 ,. 22 ... Martin and Sand>Numerous, in company w!th swallows 

 Mart n / in the Derwent Vallej'. 



28 ... Blackcap Warbler ... First seen, but silent; w.-iim breezes, 



.S.E.S. 



29 ... Whinchat Seen for first time, weather dull. 



S.E.S. 

 29 ... Common Sandpiper ... Seen for first lime, in pairs, in Rivelin 

 Valley. 



May 3 ... Landrail First heard, weather dull and gloomy, 



W. ' 



„ 6 ... Spotted Flycatcher ... First seen, very wet night, wind direct, 



S. These birds are still solitary. ^ 



15 ... Ring Ousel 



18 ... Chiflfchaff ... 



19 ... Swallow 



19 ... Cuckoo 



22 ... Whitethroat ... 



Dates. Species. 



Feb. 10 ... Song Thrush 



Blackbird 



.„• ...J 



Remarks. 

 .. Arrived in night; dark and cloudy, 



wind W. 

 ,. Arrived in night ; dark and cloudy, 

 wind W. 

 March 20 ... Yellow Wagtail Numerous. 



,, 20 ... Pied Wagtail ,, 



,, 29 ... Willow Warbler One specimen seen, somewhat feeble, 



silent; wind W. by S- , night dull 

 and showery, snow only left ground 

 day before. Never known this 

 species so early before. Average 

 time being April 5. 



,, 29 ... Greenfinch Again in usual haunts after being 



entirely absent during the winter, 

 with the exception of one pair seen 

 in a garden in Sheffield. 



April 9 ... ChiffchafF Saw and heard in young fir plantations 



at Hollow Meadows, S.W. and 

 westerly winds. 



,, 21 ... Curlew In pairs at breeding grounds on moors. 



,, 21 ... Ring Ousel Numerous en moors, mostly in pairs ; 



no song. 



,, 24 ... Tree Pipit Arrived; dull and showery weather, 



easterly winds. 



(On the evening of 25th not a bird was 

 seen ; on morning of 26th the birds 

 abounded and their cheery notes are 



ChiffchafFs \ heard on every side. The night was 



dark and bhowery (new moon), wind 

 S. 



26 ... Cuckoo Heard in Lees-hall Wood. This bird 



has ajTived during past night, doubt- 

 less in same flight as willow warblers, 

 &c. 



,, 28 ... Swallow Seen in Meersbrook Park ; weather 



showery and dull, wind light from 

 S.W., moonlight. 



,, 29 ... Whinchat Seen Jn Meersbrook Park ; weather 



showery and dull, wind light from 

 S.E., moonlight. 

 May 2 ... Wheatear On moors, full of scng. 



,, 2 ... Common Sandpiper ... Rivelin and Redmires damf, in pairs. 



1 his species has been here seme few 

 days. 



,, 2 ... Redstart This bird has now arrived, Vut only 



seen in small numbers. Cold easterly 

 winds, moonlight. 



,, 5 ... Wrjneck Saw on Rivelln moors ; solitary and 



uttering its whi!^tling nctes. Cold 

 easterly winds. 

 D T „„j..«'i -,„,] UTt.'*- ('Heard in meadows: very scarce; 



" Siroat . 1 probably came last iightiith a cold 

 ( south-westerly breeze. 



,, 12 ... Sand M.ortin Skimming over the waters 'in small 



numbers. This species is remark- 

 ably late ; wind N.W. by W. 



,, 13 ... Blackcap Singing in densest covers, and very 



shy. This species is very late. 

 Scuth-westerly breeze, clear night. 



„ 17 ... Martin S.aw a pair of these birds ; ihey are 



very late as compared with previous 

 seasons. Southerly breezes r.nd very 

 showery. 



,, 24 ... Swift Cne seen on the borders of the Rivelin 



Moors. South-westerly breezes and 

 very showery. 



,, 26 ... Spotted Flycatcher ... One specimen seen, silent and scme- 



what wary. N.W. by W., light, 

 and showery moonlight night. 



Such are a few extracts, taken veibatim, from my note-book ; 

 they might have been considerably increased, and the time of 

 departure noted, as well as the arrival of our winter migrants, 

 but I fear I have already trespassed too greatly on your valuable 

 space. I sincerely trust that this interesting subject will be more 

 fully discussed and studied by your correspondents and readers ; 

 for in that way many of the difficulties enshrouding the move- 

 ments of the feathered tribes will be overcome. 



Heeley, near Sheffield, June 9 Charles Di.xon 



Glow-worms v. Snails 



Your correspondent, Mr. R. S. Newall, has unconsciously 

 reversed the natural condition of affairs in his note (Nature, 

 vol. XX. p. 197). The heading should have been as above. 

 Glow-worms dezvur snails, which are their natural food. The 

 particular snail in question had probably been attacked by one 

 of the glow-worms, which had left some of its phosphorescent 

 matter adhering to it, and this occasioned the idea that it was 

 showing through the body of the mollusk. Possibly in this case 

 the snail may have proved too large for the glow-worm. An 

 allied insect, Drilus flavescens, somewhat rare in this country, 

 and not luminous, is, so far as the female is concerned, seldom 



